A recent speechby CIA director John O. Brennan at the Council on Foreign Relations mentioned geoengineering, specifically stratospheric aerosol injection.
Claim:
• CIA director John O. Brennan at the Council admits geoengineering in the form of stratospheric aerosol injection (SAI) is taking place, ie "chemtrails".

Rebuttal:
• Nowhere in his speechis there an "admission" that a SAI program is already taking place. The part where Brennan mentions geoengineering is just one example out of several, not-often-mentioned issues that CIA monitors for potential (future) elements of instability in the world. A SAI program, if ever implemented, could generate conflicts and security threats if misused. It's CIA's job to consider all types of concepts for potential future problems and threats, including science oriented concepts.

Reading the whole transcript, and the relevant parts, it becomes clear that when Brennan brings up geoengineering, he is talking about future concepts, that may never be put into practice:

This is the context of the speech:
add: time stamp 4:30 in full speech video attached below/c-span

I’ll start with the overarching challenge of instability, which continues to grip large sections of the globe.

Global instability is one of the defining issues of our time, and its implications are hard to overstate. As instability spreads, extremists and terrorists are finding sanctuary in ungoverned spaces. Energy supplies are being disrupted. Political reform is suffering as too many governments opt for authoritarian measures at the expense of democratic principles and respect for human rights.

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Here is the part where SAI is mentioned. Emphasis (bold font) has been added where there are clear indications how Brennan is talking about something that would be, could be a potential future thing:
add: timesstamp 12:30 in original video linked below/c-span

Another example is the array of technologies—often referred to collectively as geoengineering—that potentially could help reverse the warming effects of global climate change.
[...]An SAI program could limit global temperature increases, reducing some risks associated with higher temperatures and providing the world economy additional time to transition from fossil fuels.
[...]
As promising as it may be, moving forward on SAI would raise a number of challenges for our government and for the international community. On the technical side, greenhouse gas emission reductions would still have to accompany SAI to address other climate change effects, such as ocean acidification, because SAI alone would not remove greenhouse gases from the atmosphere.

On the geopolitical side, the technology’s potential to alter weather patterns and benefit certain regions at the expense of others could trigger sharp opposition by some nations. Others might seize on SAI’s benefits and back away from their commitment to carbon dioxide reductions. And, as with other breakthrough technologies, global norms and standards are lacking to guide the deployment and implementation of SAI.

It is quite clear that John O. Brennan does not talk about something that is already implemented. He talks about merely suggested technology that might be useful, but not necessarily implemented, in the challenge against abrupt anthropogenic global warming. Brennan also raise the issues with the proposed technology from a security perspective, which is what the CIA deals with every day.

This is nothing new. The goals and the problems of the proposed SAI technology is something that has been openly stated and discussed, both science and political-wise for more than a decade now. Brennan does not provide any new information on the subject.

Some interesting side points:

• Brennan mentions that an SAI program intends to combat global warming "in much the same way that volcanic eruptions do".
• Volcanic eruptions cools the earth by depositing ash and sulfur particles in the air.
• Some have suggested a connection to discredited scientist J. Marving's study on coal fly ash, claims which have been addressed and debunked here, here and here.
• The very term stratospheric aerosol injection indicates that the aerosols should be put into the stratosphere, otherwise the aerosols will cause heating instead of cooling. Common "chemtrail" lore believes that conventional airplanes are doing the "spraying", but conventional airplanes cannot fly in the stratosphere. This strongly suggests that the trailsseen behind such airplanes cannot be the product of stratospheric aerosol injection.

In each case injection is assumed to occur uniformly between 15 and 25 km, with the initial plumes distributed throughout this region to avoid hot spots.

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15km is 50,000 feet which is much higher than conventional commercial flights go. But the altitude depends on the latitude. Northern latitudes require lower altitudes. The repport also explains (my emphasis):

Our generic platform is a jet-fighter-sized aircraft carrying a payload of 10 metric tons of finely divided aerosol, or an equivalent precursor mass, to be distributed evenly over a 2500 km flight path during an 4-hour flight (while few aircraft are currently capable of sustained flight at stratospheric heights, platform design issues are neglected at this point)

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So it is important to understand that the proposed methods of SAI is neglecting obvious current delivering limitations when it comes to aircrafts. Commercial type aircrafts doesn't seem to be a viable option in this proposition.

• The very term stratospheric aerosol injection indicates that the aerosols should be put into the stratosphere, otherwise the aerosols will cause heating instead of cooling. Common "chemtrail" lore believes that conventional airplanes are doing the "spraying", but conventional airplanes cannot fly in the stratosphere. This strongly suggests that the trailsseen behind such airplanes cannot be the product of stratospheric aerosol injection.

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One remark on this; Don't they sometimes do fly in the stratosphere? Depending on definition and location used, e.g. when searching google things like these pop up:

Commercial jet aircraft fly in the lower stratosphere to avoid the turbulence which is common in the troposphere below.

Yes, commercial planes do often fly above the tropopause, ie in the stratosphere. Here in the UK the tropopause can be around 30,000ft or even lower when we have arctic air overhead. Planes regularly fly above it (and very rarely leave contrails above it, as humidity rapidly drops off above the tropopause).

This is a sounding from April, showing the tropopause (arrowed) below 30,000ft. Planes were leaving contrails around 27,000ft that day but no traffic above 30,000ft was leaving any trails.

Planes routinely fly in the lower stratosphere, yes. Most SRM proposals assume injection at 60/70kft, however. This is far beyond the reach of commercial aircraft, as well as all heavy lift military aircraft (the C-17 tops out around 45kft, while the An-124 reaches 40kft. The C-5 can't even reach 36kft).

Thank you all for the clarification. Yes, the points brought by @Spectrar Ghost is what I meant originally. While some commercial aircraft flies on the edge of the lower stratosphere, it is no where near the altitude where SAI is proposed to be ejected. I will add this to my OP for clarification. Perhaps @TWCobra can help clarify, as TWCobra is an actual pilot if I remember correctly.

Thank you all for the clarification. Yes, the points brought by @Spectrar Ghost is what I meant originally. While some commercial aircraft flies on the edge of the lower stratosphere, it is no where near the altitude where SAI is proposed to be ejected. I will add this to my OP for clarification. Perhaps @TWCobra can help clarify, as TWCobra is an actual pilot if I remember correctly.

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I brought this topic up about 4 years ago in one of my initial posts. I think the info presented there is still pretty valid. I did a Sydney-Santiago flight about two weeks ago and am fairly certain we flew in the lower stratosphere for most of the way. We also contrailed for the solid two hours of sunlight we had leaving Sydney AND saw the Aurora Australis.(flew under it as well!)

If we were dropping geoengineering materials however it would not have been particularly effective in blocking any sunlight as the sun was always either low in the sky or absent completely.

That is the point. People like David Keith say that 30 degrees either side of the equator would be the optimum region for SAI, and a quick look at the tropopause markers in the graphs in that post show how high an aircraft would have to fly to get even close. Not possible with 99.95% of current aircraft.

Our generic platform is a jet-fighter-sized aircraft carrying a payload of 10 metric tons of finely divided aerosol, or an equivalent precursor mass, to be distributed evenly over a 2500 km flight path

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This equates to 4 grams of material per kilometre. Or roughly 1 cubic centimetre of geoengineering material per flight kilometre.

The smoking gun is definitely still smoking. CIA Director John Brennan shot another round of evidence in the proof that our government is involved in climate intervention or weather warfare.

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Its sad that he takes a discussion of potential future use of SRM as a "confession" of on-going activity. Its really unfortunate that he uses his celebrity to deliberately mis-inform (disinfo) his followers into believing its a "confession" when it is no such thing. As for actual evidence? He claims to be offering that up in his next article- stay tuned:

The question is: Is there hard evidence for a government cover-up of its already-active stratospheric aerosol injection program?

To find out that answer, please don’t miss my column next week. In it, I will explain the CIA’s direct involvement in geo-engineering (particularly SAI) and demonstrate how the agency is using the National Academy of Sciences to produce a report that the Obama administration can manipulate to the public to justify its sky crimes. I’ll also show how the U.S. Senate is swallowing the pro-geo-engineering bait hook, line and sinker, and how a massive multiple-agency government gag order and unprecedented whistleblower penalties are suppressing those on the inside from leaking or confirming the feds present geo-engineering operations

My guess is they will probably do the SIA thing because places like China and India make so much pollution and they won't lower it because of their economies. The thing is that it won't be covert. Unfortunately there is no garuntee that it will even work correctly or effectively enough to make a huge difference. My brother who has a BA in geology took lots of courses that focused on climate change. He said that it's too complicated to hit with a silver bullet like SAI. Many scientists do not think SIA is a good course of action. The government is definitely consulting scientists about this issue. I just wonder why they want the CIA to do this and not NASA or the air force. Maybe it is because the CIA is a foreign intelligence agency?

The government considers climate change to be a cause of terrorism, and they are correct. Chemical companies like Dupont have a lot to gain from this whole thing and does some hawkish stuff, which works for conservatives, and fighting global warming works for the liberals. It's an easy sell to a congress who desperately needs to make something work. My brother says the earth has a way of fixing itself regardless, even if it means making human life impossible. So I figure it won't really matter if they do SIA or not. It's not going to be a big secret if they do it, but it may not work the way they plan because of how complex the atmospheric system is. This stuff is a low health concern, and the elites have to breathe the same air as all of us, so I don't really give a shit what happens at this point.

CIA monitors for potential (future) elements of instability in the world. A SAI program, if ever implemented, could generate conflicts and security threats if misused. It's CIA's job to consider all types of concepts for potential future problems and threats, including science oriented concepts.

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The Central Intelligence Agency gathers Intelligence. NASA has no means of gathering Intelligence on other countries. And the Air Force's job isn't to gather Intelligence either.

My guess is they will probably do the SIA thing because places like China and India make so much pollution and they won't lower it because of their economies. The thing is that it won't be covert. Unfortunately there is no garuntee that it will even work correctly or effectively enough to make a huge difference. My brother who has a BA in geology took lots of courses that focused on climate change. He said that it's too complicated to hit with a silver bullet like SAI. Many scientists do not think SIA is a good course of action. The government is definitely consulting scientists about this issue. I just wonder why they want the CIA to do this and not NASA or the air force. Maybe it is because the CIA is a foreign intelligence agency?

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The CIA is involved because global warming (GW, and it's effects) can become a security issue in the future (global flooding and/or results that can destabilize nations), and it's not out-of-the-ordinary to consider these things, for any governmental agency. Countless other gov't agencies are also considering the future effects of GW, and just because the CIA is doing it too, is no big deal. One lesson learned from 911, was that agencies should work together and share common issues....but some 'agencies' have a distasteful taboo among the suspicious.

The government considers climate change to be a cause of terrorism, and they are correct. Chemical companies like Dupont have a lot to gain from this whole thing and does some hawkish stuff, which works for conservatives, and fighting global warming works for the liberals. It's an easy sell to a congress who desperately needs to make something work......

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I think it's presumptive to claim companies and regulatory gov't are happy and complicit about climate change.

• The very term stratospheric aerosol injection indicates that the aerosols should be put into the stratosphere, otherwise the aerosols will cause heating instead of cooling. Common "chemtrail" lore believes that conventional airplanes are doing the "spraying", but conventional airplanes cannot fly in the stratosphere. This strongly suggests that the trailsseen behind such airplanes cannot be the product of stratospheric aerosol injection

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This is from PhysLink:

"The World record for both speed and height by an air-breathing aircraft (not a rocket) was 85,135 feet. It was set in an SR-71 Blackbird in 1976. The speed record is also held by an SR-71, at 2,193 mph. This is not as high or as fast as the airplane can fly, however, it's absolute speed and altitude limits are classified. Most US military aircraft can exceed 50,000 feet, if they really really try. Again, the limits are classified."

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and

"A typical commercial jet (most standard flights) cruises at around 28-35,000ft (up to 6.6 miles of altitude). The main exception is Concorde which was designed to fly at a higher altitude (and hence lower wind resistance) at around 45,000ft. Although many jets could fly at higher altitudes, they are usually certified to an altitude giving a wide safety margin. For example the new generation Boeing 737 is certified to 41,000ft (7.8 miles).

Many military jet aircraft are able to fly considerably higher. Often, the plane itself is not pressurised and instead the pilot wears a pressure suit that provides him with a pressurised environment. Originally, very high altitude military planes were used for surveillance ï¿½ the current versions of the famous U2 spy plane, originally designed in the 1950s can cruise at up to 90,000ft (17 miles). The Stealth Bomber cruises at up to 50,000ft (8.3 miles) and many other combat planes can now also attain significant altitudes."

Another question I have is, with the relatively consistent history of our government not being extremely honest with the citizens, how can we know for sure that a project isn't already implemented in some way, perhaps still in an experimental or trial phase, just because the head of the CIA used words like "would" and "could". If they started doing this today, how long would it be before we saw any results from it? Would it be immediate? If not, then are words like "would" or "could" really signs that he is referring to a program that has not yet been implemented, or could it be that we have yet to see the results he is saying the program "could" produce?

Also, isn't it a pretty well known thing that the general population never knows the full capability and technology of the government? That the government are years or decades ahead of the technology that is publicly available? If that is the case, and the above quoted article mentions that the government has been able to fly planes well above the 60-70k feet that Spectrar Ghost mentioned in this quote:

Most SRM proposals assume injection at 60/70kft, however. This is far beyond the reach of commercial aircraft, as well as all heavy lift military aircraft (the C-17 tops out around 45kft, while the An-124 reaches 40kft. The C-5 can't even reach 36kft).

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How could I convince someone that the government does not have planes that fly that high when the article I linked states that "Originally, very high altitude military planes were used for surveillance ï¿½ the current versions of the famous U2 spy plane, originally designed in the 1950s can cruise at up to 90,000ft (17 miles). The Stealth Bomber cruises at up to 50,000ft (8.3 miles) and many other combat planes can now also attain significant altitudes.". If the government had planes that could cruise at 90k feet in the 1950's, how could I possibly convince someone that 60-70k is too high for them today?

Just to be clear, I am not a chemtrail person, but I am having an ongoing debate with some very intelligent friends and they keep making good points that I can't quite argue against. Came here hoping to find solid, unquestionable proof, but the proof provided in this article seems pretty shaky, and some of the claims used to debunk seem pretty inaccurate, according to PhysLink.

Are these smart people you're debating with claiming otherwise? That'd be a good place to start showing them their errors.

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They claim that, if it is a government program, which the government was trying to keep somewhat under wraps, then there would be no reason that a type of plane could not be created that would externally resemble a commercial jet, but be able to fly higher and carry the aerosol payload and distribution mechanism. The argument there is that citizens would become even more concerned more quickly and be easier to believe if people were constantly seeing military jets flying above.

They claim that, if it is a government program, which the government was trying to keep somewhat under wraps, then there would be no reason that a type of plane could not be created that would externally resemble a commercial jet, but be able to fly higher and carry the aerosol payload and distribution mechanism. The argument there is that citizens would become even more concerned more quickly and be easier to believe if people were constantly seeing military jets flying above.

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i think the point is there is no proof. Chemtrailists point to contrails as proof, but the vast vast majority of the time the exact plane can be identified. And they arent military. (obviously once in a while they are military as military planes fly too).

Even "if" some SRM experiments were happening now, there is absolutely nothing that indicates they would look anything like contrails.

They claim that, if it is a government program, which the government was trying to keep somewhat under wraps, then there would be no reason that a type of plane could not be created that would externally resemble a commercial jet, but be able to fly higher and carry the aerosol payload and distribution mechanism. The argument there is that citizens would become even more concerned more quickly and be easier to believe if people were constantly seeing military jets flying above.

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But to people on the ground any plane, commercial, military or whatever, at 38,000ft plus is all but invisible unless it is laying a contrail. A tiny spec in the sky is a tiny spec in the sky, even if it is contrailing, and without a camera with a very big lens, top notch binoculars, a powerful spotterscope etc, it is impossible to distinguish the type of plane it is, let alone marking. So most planes go un-noticed anyway. The only people who will use the equipment required to identify the plane are hard core aviation enthusiasts - who will probably know exactly what they are seeing anyway; or chemtrail theorists who probably wouldn't, so why go through all the rig-moral of complex sub-diffuse, when most people wouldn't even notice?

They claim that, if it is a government program, which the government was trying to keep somewhat under wraps, then there would be no reason that a type of plane could not be created that would externally resemble a commercial jet, but be able to fly higher and carry the aerosol payload and distribution mechanism. The argument there is that citizens would become even more concerned more quickly and be easier to believe if people were constantly seeing military jets flying above.

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It's worth noting here that credible stratospheric aerosol plans envision laying about ten million tons of SO2 annually. This would require thousands of aircraft to fly hundreds of thousands of flights per year. Presuming you could build and fly these aircraft for about the same as an A320 ($99M aircraft cost, $8500/hr flight cost), you would be spending ~$200B on aircraft, and ~$34B annually on flight time. This is not an expense that could go unnoticed. Nor is the number of necessary employees - the thousands of flight crew and accompanying logistics chain - conducive to a secret program.

Our generic platform is a jet-fighter-sized aircraft carrying a payload of 10 metric tons of finely divided aerosol, or an equivalent precursor mass, to be distributed evenly over a 2500 km flight path during an 4-hour flight (while few aircraft are currently capable of sustained flight at stratospheric heights, platform design issues are neglected at this point). The initial plume cross section is taken to be 1 m2, which is consistent with the dimensions of the platform. Note that, with these specifications, a total aerosol mass injection of 10 Tg of particles per year would call for 1 million flights, and would require several thousand aircraft operating continuously in the foreseeable future. To evaluate other scenarios or specifications, the results described below may be scaled to a proposed fleet or system.

I tend to believe the chemtrails theory is hysteria. Which is why I was surprised when stumbling across this in the school newspaper. What is John Brennan talking about when he addressed an audience of students of Rensselaer Polytechnic Institute in November 2016. I happened to be reading because I am alumni. I quote from The Poly, the school newspaper, link below ...

Brennan then transitioned to questions from the audience. He said that some of the new global issues that he is paying attention to are biological agents, genetic editing, stratospheric aerosol injection, and added that technology is a double-edged sword.

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However, those are not his direct words, its an account from the college newspaper. So I like original direct sources of exactly what he said in his own words, so I went looking, he said this during the question and answer period. I found the only video of it online at YouTube, the video was put on YouTube by RPI, however, they edited out the question and answer section completely.

My guess is that because he addresses global warming and its effects in the video that he was referring to future technology to combat the effects of global warming. But as he points out, technology is a double-edged sword. The CIA did use stratospheric aerosal injection in the 70s in Vietnam trying to prolong the monsoon season so the Ho Chi Minh trail would stay muddy and less effective for more of the year. So they have had this tech for a long time I imagine. But alas, no direct source on what he actually said so I guess we'll never know.

I'm not convinced. As an example, there was a gap of 10-12 years in between the time the first stealth aircraft were flown to when they were publicly acknowledged. And during that time the possibility of their existence was denied. Then when it couldn't be denied any longer, they went public. In the case of SIA's or "chemtrails" they're not just going to come out & say that they've been doing this for a number of years. Instead it will come out slowly, confirming that what we've considered conspiracy theories are in reality, facts.

I'm not convinced. As an example, there was a gap of 10-12 years in between the time the first stealth aircraft were flown to when they were publicly acknowledged. And during that time the possibility of their existence was denied. Then when it couldn't be denied any longer, they went public. In the case of SIA's or "chemtrails" they're not just going to come out & say that they've been doing this for a number of years. Instead it will come out slowly, confirming that what we've considered conspiracy theories are in reality, facts.

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But what he is saying here is not an admission, which is the point of this post.

That does not mean there's not a secret program leaving no evidence. It just means that this speech is not evidence of covert geoengineering.